This invention relates to an improved jack device of the type used in constructing grain bins and the like.
One technique for assembling grain bins in place is a top to bottom construction method. The top of the bin is first constructed and is initially held a short distance above the ground by a series of jacks in order for workers to successively add the lower portions of the bin while working essentially at ground level. Each added section of the bin is a circular panel which is secured to the lower edge of the next higher panel. The bin is intermittently raised by the jacks so that the panel sections may be added in succession by the workers without requiring them to work on ladders, scaffolds or the like.
As can be appreciated, the bin jacks which provide the sole support for the bin during the construction process must be sturdy devices and must be able to raise even the largest bins relatively easily and without undue delay each time a panel section is to be added to the bin.
The main problem with conventional jacks is that they lack the overall strength and stability required to handle large grain bins. It is common for the jack to rear up under the force of the large weights which are applied and which tend to topple the jack inwardly toward the bin, thus creating a hazard to workmen. A need therefore remains for a stronger and safer bin jack. The principal goal of the present invention is to meet that need.
More specifically, it is an object of the invention to provide a bin jack which is able to handle even the largest bins with enough stability to effectively resist the forces tending to upset the frame. In this respect, a multiple pulley system is utilized to distribute the load forces over the frame in a uniform fashion to increase the stability and provide resistance to the moment forces which tend to overturn the jack.
Another object of the invention is to provide a bin jack of the character described which is improved structurally and which is capable of handling the largest bins with ease.
In conjunction with the preceding object, it is an additional object of the invention to provide a bin jack wherein a sufficient mechanical advantage is obtained to permit the use of a manual winch for handling the largest loads that are encountered.
A further object of the invention is to provide a bin jack of the character described which is constructed with an inclined and extended brace leg. In conjunction with the multiple pulley system, weight is transferred to the relatively long brace leg to increase stability without requiring excessively heavy structural members.
Yet another object of the invention is to provide a bin jack of the character described which is simple and economical to construct and which requires minimal maintenance and repair.
Other and further objects of the invention, together with the features of novelty appurtenant thereto, will appear in the course of the following description of the drawings.